Key Facts
- Phases
- Two phases: Trio I and Trio II
- Date range
- 20 April – 13 May 1942
- Area of operations
- Eastern Bosnia, between Sarajevo and the Drina river
- Partisans remaining after operation
- ~600 fighters left in eastern Bosnia
- Part of
- Third Enemy Offensive (Yugoslav historiography)
Strategic Narrative Overview
Conducted in two phases from 20 April to 13 May 1942, the operation was hampered by preemptive Ustaše actions, Italian delays, and mutual suspicion across the German-Italian demarcation line. Both insurgent factions largely avoided direct confrontation with Axis forces, instead fighting each other. Chetnik propaganda and communist sectarian policies drove mass defections from Partisan detachments, with violent coups toppling communist leadership in nearly all eastern Bosnian Partisan units, effectively delivering those detachments to the Chetniks.
01 / The Origins
By early 1942, eastern Bosnia within the German-Italian-occupied Independent State of Croatia was plagued by two insurgencies: the communist-led Yugoslav Partisans and the Serb-nationalist Chetniks. Axis forces, alarmed by the scale of rebellion, planned a coordinated sweep to eliminate insurgents between Sarajevo and the Drina river. The operation also involved Ustaše militia and Croatian Home Guard units, representing the first major combined German-Italian counter-insurgency effort of the war in the region.
03 / The Outcome
After the operation, Tito withdrew with his Supreme Headquarters and the 1st and 2nd Proletarian Brigades from Foča toward western Bosnia in the Partisan Long March. Only around 600 Partisans remained in eastern Bosnia. The Chetnik movement was significantly strengthened by mass Partisan defections and temporarily controlled large parts of the region, making accommodations with the Ustaše regime in May and June 1942. The operation achieved only limited military success against the insurgencies.
Belligerents & Mobilization Analysis
Side A
3 belligerents
Side B
2 belligerents
Josip Broz Tito.
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.